Compounds such as polychlorinated biphenyls (PCBs), dichloro-diphenyl trichloroethane (DDT), trichloroethylene (TCE), and chlorinated benzenes have been found to be persistent compounds in the environment. Due to spills and prior usage, these compounds are often found in soil, sludge and building materials. Their disposal requires a safe and efficient means.
Various methods for the removal or destruction of halogenated organic compounds are known. For example, the Peterson U.S. Pat. No. 4,574,013 discloses a process wherein a heated slurry of contaminated soil is treated with a mixture of an alkaline constituent and a sulfoxide catalyst. This process is disadvantageous in that the sulfoxide catalyst may transport contaminants into living systems, the sulfoxide catalyst produces odorous compounds when heated to high temperatures and decomposes into combustible by-products, and the process requires large amounts of reagents.
Additionally, polychlorinated biphenyls in contaminated soils have been reduced by the use of incineration and surfactant-assisted washing. These methods are quite costly or require complex operations. For example, surfactant-assisted soil-washing requires many unit operations in order to remove the polychlorinated biphenyls from the soil and to regenerate the surfactant wash solution.
Copending and commonly assigned patent application, entitled "Process for Remediation of a Contaminated Particulate Material," filed May 16, 1994, Ser. No. 08/242,768, discloses a method that removes halogenated organic contaminants from particulated material by utilizing a thermal desorption sweep with a vapor stream containing water and an amine or amide organic additive. The contaminated material is cleaned using the process at ambient pressure and a temperature between about 250.degree.-340.degree. C.
A need exists for a method to remediate contaminated materials which is relatively inexpensive and obtains acceptable removal levels of halogenated organic contaminants from particulate material at temperatures between about 300.degree.-400.degree. C. There is also a need for a method that can utilize sodium salts and ammonium salts to substantially remove halogenated organic contaminants from particulate material.